Nickel/Lewis Acid-Catalyzed Cyanoesterification and Cyanocarbamoylation of Alkynes

Cyanoformates and cyanoformamides are found to add across alkynes by nickel/Lewis acid (LA) cooperative catalysis to give β-cyano-substituted acrylates and acrylamides, respectively, in highly stereoselective and regioselective manners. The resulting adducts serve as versatile synthetic building blocks through chemoselective transformations of the ester, amide, and cyano groups as demonstrated by the synthesis of typical structures of β-cyano ester, β-amino nitrile, γ-lactam, disubstituted maleic anhydride, and γ-aminobutyric acid. The related reactions of cyanoformate thioester and benzoyl cyanide, on the other hand, are found to add across alkynes with decarbonylation in the presence of a palladium/LA catalyst.

研究发现，在镍/路易斯酸（Lewis acid, LA）协同催化下，氰基甲酸酯（cyanoformates）与氰基甲酰胺（cyanoformamides）可分别与炔烃（alkynes）发生加成反应，以高度立体选择性和区域选择性的方式得到β-氰基取代丙烯酸酯与β-氰基取代丙烯酰胺。所得加成产物可通过对酯基、酰胺基与氰基的化学选择性转化，作为多用途合成砌块；文中通过合成β-氰基酯、β-氨基腈、γ-内酰胺、二取代马来酸酐及γ-氨基丁酸的典型结构，证实了该类转化的实用性。另一方面，在钯/路易斯酸催化剂存在下，氰基甲酸硫酯与苯甲酰氰可与炔烃发生伴随脱羰反应的加成反应。